Cells Survive Extreme Water Loss

resurrection fern leaves growing off of a log with backlight from the sun

Biological Strategy

Resurrection fern

AskNature Team

Image: Katja Schulz / Flickr / Some rights reserved

Protect From Loss of Liquids

Water is essential to life. Liquids, mostly water, make up 70 to 90% of all living systems, and the loss of even a small percentage can mean the difference between life and death. Living systems must maintain a proper liquid balance, which is especially difficult in dry conditions. To do so, they must control the movement of liquids across their boundaries. Living systems do this using structures or waterproof materials to prevent or slow liquid movement. For example, when humans receive a cut, they must limit blood loss. Scattered throughout the bloodstream are lens-shaped structures that serve to plug the wound.

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Ferns

Class Polypodiopsida (“many footed appearance”): Ferns, horsetails, whisk ferns

Ferns are a class of plants that reproduce without flowers or seeds, but by spores. With over 10,500 known species, ferns are the second most abundant group of vascular plants after angiosperms (flowering plants). Though they can be found in a variety of habitats, ferns prefer moist, humid environments. Ferns first evolved in the Carboniferous Period about 360 million years ago. Today, ferns are grown for food, medicine, ornamental landscaping, and hold importance in culture and folklore. Several species can also remove pollutants from the atmosphere.

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The cells of resurrection ferns may survive extreme water loss thanks to dehydrin proteins.

“[S]ome plants, like the aptly named ‘resurrection fern’ (Polypodium polypodioides), can survive extreme measures of water loss, even as much as 95% of their water content. How do the cells in these desiccation-tolerant plants remain viable?

“…Ronald Balsamo, Associate Professor of Biology at Villanova University and Bradley Layton, Associate Professor of Mechanical Engineering and Mechanics at Drexel University…found that not only is a particular class of proteins, called dehydrins, more prevalent during dry conditions, but, for the first time, they found that it was also prevalent near the cell walls. Dehydrins earned their name for their ability to attract, sequester, and localize water. They behave this way because of their negative charge.

“The finding led the researchers to the conclusion that these water-surrounded dehydrins may actually allow water to act as a lubricant between either the plant cell membrane and the plant cell wall or even between individual cell wall layers.” (ScienceDaily 2010)

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http://www.sciencedaily.com/releases/2010/04/100401101053.htm
http://www.amjbot.org/cgi/content/full/97/4/535